Who caused the Regina riot and why?

When the Great Depression hit, places like Saskatchewan were hit especially hard. While families, women, and children were often helped by Canadian agencies, single unemployed men had no where to turn... Except to work camps. Work camps allowed men to earn money, but under harsh conditions. They were payed 20 cents per day to replace roads, bridges, and deepen lakes. The living conditions were harsh, as were working conditions. Soon men began to lash out. They created the On-To-Ottawa trek to express their feelings to the Saskatchewan government. The plan was for the men to travel to Ottawa and speak to the Prime Minister at the time, R. B. Bennett. Hundreds of men took to box cars on the trip to Regina. When they arrived, two men in Bennett's cabinet, Robert Manion and Robert Weir, granted the protest's 8 leaders to join Bennett in Ottawa under the condition that the rest of the protesters stay in Regina. Arthur "Slims" Evans, the leader of the trek and the seven others attended the meeting in which Bennett accused all of them as radicals and Evans an extortionist. Arthur replied by calling Bennett a liar before being escorted out of the building. When Evans returned back to Regina, with the seven others, he, along with many other trekkers, discovered that road blocks prevented any protesters from leaving Regina. He held a meeting with about 2,000 in attendance, in which only about 300 trekkers attended, when the whole gathering was jumped by the RCMP riot squads...